Plate laminate type heat exchanger

ABSTRACT

Problem to be Solved A plate laminate type heat exchanger having high heat exchange efficiency is provided. 
     Solution In a plate laminate type heat exchanger  100 , a plurality of groove-like protrusions  10  is formed on one side of each of flat core plates  53  and  54 , and the protrusions  10  extend substantially in parallel to one another from one end side in the longitudinal direction of the plate toward the other end side in the longitudinal direction of the plate, form a U-turn region in an area on the other end side in the longitudinal direction of the plate, and return to the one end side in the longitudinal direction of the plate. The plate is curved in such a way that ridges and valleys are formed on part of the plate, the area in which the protrusions  10  are formed but the U-turn region is not formed, in the direction in which the plate is laminated and the ridges and valleys are repeated along the longitudinal direction. Both ends of each of the protrusions  10  converge into an inlet port for high temperature fluid  58   a  and an outlet port for high temperature fluid  58   b , respectively. A pair of core plates  53  and  54  (core  55 ) is assembled in such a way that the side of one of the two core plates  53  and  54  that is opposite the one side faces the side of the other one of the two core plates  53  and  54  that is opposite the one side and the protrusions  10  and  10  formed on the respective core plates are paired but oriented in opposite directions.

TECHNICAL FIELD

The present invention relates to a plate laminate type heat exchanger,such as an oil cooler and an EGR cooler.

BACKGROUND ART

FIG. 7 shows an example of a plate laminate type heat exchanger ofrelated art. A plate laminate type heat exchanger 500 shown in FIG. 7includes front and rear end plates 51 and 52 and a plurality of pairs ofcore plates 53 and 54 (cores 55) laminated therebetween, and peripheralflanges of each of the pairs of core plates 53 and 54 (a peripheralflange 53 a and a peripheral flange 54 a, for example) are bonded toeach other in a brazing process, whereby high temperature fluid and lowtemperature fluid compartments are defined by alternately laminating inthe space surrounded by the end plates 51, 52 and the core plates 53,54, and each of the fluid compartments communicates with pairs ofcirculation pipes 56 a, 56 b and 57 a, 57 b provided on the front endplate 51 in such a way that the circulation pipes jut therefrom. Anintermediate core plate 27 having fins 25 formed thereon is interposedbetween each pair of the core plates 53 and 54 (see Japanese PatentLaid-Open Nos. 2001-194086 and 2007-127390, for example).

Each of the core plates 53 and 54 has a substantially flat-plate shape.An outlet port for high temperature fluid 58 b and an inlet port for lowtemperature fluid 59 a are provided in each of the core plates 53 and 54on one end side in the longitudinal direction thereof. On the otherhand, an inlet port for high temperature fluid 58 a and an outlet portfor low temperature fluid 59 b are provided in each of the core plates53 and 54 on the other end side in the longitudinal direction thereof.The inlet port for high temperature fluid 58 a and the outlet port forhigh temperature fluid 58 b, as well as the inlet port for lowtemperature fluid 59 a and the outlet port for low temperature fluid 59b of each of the core plates 53 and 54 are disposed in the vicinity ofthe respective corners thereof, and the pair of the inlet port for hightemperature fluid 58 a and the outlet port for high temperature fluid 58b and the pair of the inlet port for low temperature fluid 59 a and theoutlet port for low temperature fluid 59 b of each of the core plates 53and 54 are located substantially on the respective diagonal linesthereof. Each of the pairs of core plates 53 and 54 form a core 55. Ahigh temperature fluid compartment through which the high temperaturefluid (oil or EGR gas, for example) flows is defined in each of thecores 55. On the other hand, a low temperature fluid compartment throughwhich the low temperature fluid (cooling water, for example) flows isdefined between cores 55. The high temperature fluid compartments andthe low temperature fluid compartments communicate with the circulationpipes 56 a, 56 b and the circulation pipes 57 a, 57 b, respectively. Thehigh temperature fluid and the low temperature fluid are introduced intothe respective fluid compartments or discharged out of the respectivefluid compartments via the circulation pipes 56 a, 56 b and thecirculation pipes 57 a, 57 b. The high temperature fluid and the lowtemperature fluid, when flowing through the respective fluidcompartments, exchange heat via the core plates 53 and 54. FIG. 8 showsthe heat exchange process. The core plate shown in FIG. 8 differs fromthe core plate shown in FIG. 7 in terms of shape. In FIG. 8, theportions that are the same as or similar to those in FIG. 7 have thesame reference characters.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

As shown in FIG. 8, the high temperature fluid and the low temperaturefluid flow substantially linearly from the inlet ports 58 a and 59 atoward the outlet ports 58 b and 59 b. The core plates 53 and 54therefore have large areas that do not contribute to the heat transfer,that is, the heat exchange between the high temperature fluid and thelow temperature fluid (see the portions V in FIG. 8). As a result, theplate laminate type heat exchanger 500 of related art has a problem oflow heat exchange efficiency.

The present invention has been made in view of the problem describedabove. An object of the present invention is to provide a plate laminatetype heat exchanger having high heat exchange efficiency.

Means for Solving the Problems

To solve the problem described above, the present invention provides aplate laminate type heat exchanger comprising front and rear end plates;a plurality of pairs of core plates laminated between the front and rearend plates; and high temperature fluid compartments through which hightemperature fluid flows and low temperature fluid compartments throughwhich low temperature fluid flows defined in the space surrounded by theend plates and the core plates by bonding peripheral flanges of each ofthe pairs of core plates to each other in a brazing process, each of thefluid compartments communicating with a pair of circulation pipesprovided on the front or rear end plate in such a way that thecirculation pipes jut therefrom. The plate laminate type heat exchangeris characterized by the following features: A plurality of groove-likeprotrusions is formed on one side of each of the flat core plates. Theprotrusions extend substantially in parallel to one another from one endside in the longitudinal direction of the plate toward the other endside in the longitudinal direction of the plate, form a U-turn region inan area on the other end side in the longitudinal direction of theplate, and return to the one end side in the longitudinal direction ofthe plate. The plate is curved in such a way that ridges and valleys areformed on part of the plate, the area in which the protrusions areformed but the U-turn region is not formed, in the direction in whichthe plate is laminated and the ridges and valleys are repeated along thelongitudinal direction. A pair of an inlet port for low temperaturefluid and an outlet port for low temperature fluid are provided on therespective end sides in the longitudinal direction of the core plates,and a pair of an inlet port for high temperature fluid and an outletport for high temperature fluid are provided on one end side in thelongitudinal direction of the core plates in an area inside the areawhere the inlet port for low temperature fluid or the outlet port forlow temperature fluid is provided. Both ends of each of the protrusionsconverge into the inlet port for high temperature fluid and the outletport for high temperature fluid, respectively. Each of the pairs of coreplates is assembled in such a way that the side of one of the two coreplates that is opposite the one side faces the side of the other one ofthe two core plates that is opposite the one side and the protrusionsformed on the respective core plates are paired but oriented in oppositedirections.

The present invention is also characterized in that each of theprotrusions also has ridges and valleys formed in the width direction ofthe core plates perpendicular to the longitudinal direction of the coreplates, and the ridges and valleys are repeated along the longitudinaldirection of the core plates.

The present invention is also characterized in that the protrusionsformed on each of the pairs of core plates are the same in terms of theperiod and the amplitude of the waves formed of the ridges and valleysformed in the width direction of the core plates.

The present invention is also characterized in that the protrusionsmeander in an in-phase manner along the longitudinal direction of thecore plates.

The present invention is also characterized in that each of the pairs ofcore plates form a plurality of serpentine tubes surrounded by the wallsof the protrusions, and the serpentine tubes form the corresponding hightemperature fluid compartment.

The present invention is also characterized in that the serpentinetubes, except the one disposed in the innermost position on the coreplates, are configured in such a way that a serpentine tube having ashorter length has a smaller cross-sectional area.

The present invention is also characterized in that the protrusionsmeander in an anti-phase manner along the longitudinal direction of thecore plates.

The present invention is also characterized in that second protrusionsare formed on the walls that form the protrusions along the directionsubstantially perpendicular to the direction in which the hightemperature fluid flows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a plate laminate type heatexchanger 100;

FIG. 2 shows how high temperature fluid and low temperature fluidexchange heat via a core plate 53 in a plate laminate type heatexchanger 100;

FIG. 3A is a perspective view showing an improved portion of a platelaminate type heat exchanger 200;

FIG. 3B is a side view showing the improved portion of the platelaminate type heat exchanger 200;

FIG. 4A is a perspective view of the plate laminate type heat exchanger200 in which second protrusions 50 are formed;

FIG. 48 is an enlarged view showing part of FIG. 4A;

FIG. 5 is a perspective view showing an improved portion of a platelaminate type heat exchanger 300;

FIG. 6A is an enlarged view showing an improved portion of a platelaminate type heat exchanger 400;

FIG. 6B is a schematic plan view showing the improved portion of theplate laminate type heat exchanger 400;

FIG. 7 is an exploded perspective view of a plate laminate type heatexchanger 500 of prior art; and

FIG. 8 shows how high temperature fluid and low temperature fluidexchange heat via a core plate 53 in the plate laminate type heatexchanger 500 of prior art.

DESCRIPTION OF SYMBOLS

-   10, 30, 40 protrusion-   50 second protrusion-   58 a inlet port for high temperature fluid-   58 b outlet port for high temperature fluid-   59 a inlet port for low temperature fluid-   59 b outlet port for low temperature fluid-   100, 200, 300, 400 plate laminate type heat exchanger

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below withreference to the accompanying drawings.

FIG. 1 is an exploded perspective view of a plate laminate type heatexchanger 100 according to the embodiment of the present invention. FIG.2 shows how high temperature fluid and low temperature fluid exchangeheat via a core plate 53 in the plate laminate type heat exchanger 100.While the plate laminate type heat exchanger 100 and the core plates 53shown in FIG. 1 differ from the plate laminate type heat exchanger 100and the core plate 53 shown in FIG. 2, the portions shown in FIGS. 1 and2 that are the same as or similar to each other have the same referencecharacters. In FIGS. 1 and 2, the portions that are the same as orsimilar to those shown in FIGS. 7 and 8 have the same referencecharacters.

The plate laminate type heat exchanger 100 shown in FIGS. 1 and 2includes front and rear end plates 51 and 52 and a plurality of pairs ofcore plates 53 and 54 (cores 55) laminated therebetween, and peripheralflanges of each of the pairs of core plates 53 and 54 (a peripheralflange 53 a and a peripheral flange 54 a, for example) are bonded toeach other in a brazing process, whereby high temperature fluidcompartments through which high temperature fluid flows and lowtemperature fluid compartments through which low temperature fluid flowsare defined in the space surrounded by the end plates 51, 52 and thecore plates 53, 54, and each of the fluid compartments communicates withpairs of circulation pipes 56 a, 56 b and 57 a, 57 b provided on thefront end plate 51 in such a way that the circulation pipes juttherefrom. The end plates 51 and 52 have raised and recessed portionsformed thereon as appropriate in accordance with the shapes of the coreplates 53 and 54. The core plate 53 shown in FIG. 2 has embossments 11and slit-shaped second protrusions 50 formed thereon. No embossments 11or second protrusions 50 are shown on the core plate 53 shown in FIG. 1.

Each of the core plates 53 and 54 is formed by curving a flat plate.Specifically, a plurality of groove-like protrusions 10 is formed on oneside of the flat plate, and the protrusions 10 a to 10 e extendsubstantially in parallel to one another from one end side in thelongitudinal direction of the plate toward the other end side in thelongitudinal direction of the plate, form a U-turn region in an area onthe other end side in the longitudinal direction of the plate, andreturn to the one end side in the longitudinal direction of the plate.Ridges and valleys are formed on part of the plate, the area in whichthe protrusions 10 a to 10 e are formed but the U-turn region is notformed, in the direction in which the plate is laminated, and the ridgesand valleys are repeated along the longitudinal direction of the plate.The plate is thus curved and the outer shape thereof is designed asappropriate. No ridges or valleys are formed in the area where theU-turn region is formed because it is intended not to reduce the heatexchange efficiency. That is, since the high temperature fluid tends notto flow smoothly in the area where the U-turn region is formed, there isa concern that forming the ridges and valleys described above in thatarea reduces the heat exchange efficiency against the originalintention. No ridges or valleys are therefore formed in that area.

The protrusions 10 a to 10 e described above have ridges and valleysformed in the direction in which the core plate 53 is laminated, and theridges and valleys are periodically repeated along the longitudinaldirection of the core plate 53. The protrusions 10 a to 10 e also haveridges and valleys formed in the width direction of the core plate 53,and the ridges and valleys are periodically repeated along thelongitudinal direction of the core plate 53. The wave formed of theridges and valleys formed in the direction in which the core plate 53 islaminated and the wave formed of the ridges and valleys formed in thewidth direction of the core plate 53 have the same wave period. Further,the protrusions 10 and 10 formed on a pair of core plates 53 and 54 areconfigured to not only be the same in terms of the period and theamplitude of the wave formed of the ridges and valleys formed in thewidth direction of the core plates 53 and 54 but also meander along thelongitudinal direction of the core plates 53 and 54 in an in-phasemanner.

A pair of an inlet port for low temperature fluid 59 a and an outletport for low temperature fluid 59 b are provided on the respective endsides in the longitudinal direction of the core plates 53 and 54. Forexample, in the core plate 53 shown in FIG. 2, the inlet port for lowtemperature fluid 59 a is provided on the lower end side of the coreplate 53, and the outlet port for low temperature fluid 59 b is providedon the upper end side of the core plate 53. Further, a pair of an inletport for high temperature fluid 58 a and an outlet port for hightemperature fluid 58 b are provided on one end side in the longitudinaldirection of the core plates 53 and 54 (that is, in the area oppositethe area in which the U-turn region described above is formed),specifically, in an area inside the area where the inlet port for lowtemperature fluid 59 a is provided. For example, in the core plate 53shown in FIG. 2, a pair of the inlet port for high temperature fluid 58a and the outlet port for high temperature fluid 58 b are provided onthe lower end side of the core plate 53 on both end sides in the widthdirection of the core plate 53 in an area inside the area where theinlet port for low temperature fluid 59 a is provided (that is, in anarea above the inlet port for low temperature fluid 59 a). The inletport for high temperature fluid 58 a, the outlet port for hightemperature fluid 58 b, the inlet port for low temperature fluid 59 a,and the outlet port for low temperature fluid 59 b are designed asappropriate in terms of the cross-sectional shapes thereof.

Both ends of each of the protrusions 10 converge into the inlet port forhigh temperature fluid 58 a and the outlet port for high temperaturefluid 58 b, respectively. Each of the pairs of core plates 53 and 54(cores 55) is assembled in such a way that the side of the core plate 53that is opposite the one side described above faces the side of the coreplate 54 that is opposite the one side described above and theprotrusions 10 and 10 formed on the respective core plates are pairedbut oriented in opposite directions. The pair of core plates 53 and 54form a plurality of serpentine tubes surrounded by the walls of theprotrusions 10 and 10, and the serpentine tubes form the correspondinghigh temperature fluid compartments.

The serpentine tubes, except the one disposed in the innermost positionon the core plates 53 and 54, are configured in such a way that aserpentine tube having a shorter length, that is, a serpentine tubehaving a shorter length of the U-shaped path between the convergingportion leading to the inlet port for high temperature fluid 58 a andthe converging portion leading to the outlet port for high temperaturefluid 58 b, has a smaller cross-sectional area. Conversely, a serpentinetube having a longer length has a larger cross-sectional area. Morespecifically, the serpentine tubes, except the one disposed in theinnermost position on the core plates 53 and 54 (that is, the serpentinetube formed by the protrusions 10 e and 10 e), are configured in such away that a serpentine tube disposed in a position closer to the centerof the core plates 53 and 54 and farther apart from the outer ends inthe width direction of the core plates 53 and 54 has a smallercross-sectional area. The reason why the cross-sectional area of theserpentine tube disposed in the innermost position on the core plates 53and 54 is greater than the cross-sectional area of the outer serpentinetube adjacent thereto (that is, the serpentine tube formed by theprotrusions 10 d and 10 d) is to improve the flow of the hightemperature fluid flowing through the serpentine tube disposed in theinnermost position. That is, since the serpentine tube disposed in theinnermost position on the core plates 53 and 54 is curved more sharplyin the U-turn region described above than the other serpentine tubesare, the high temperature fluid tends not to flow smoothly through thatserpentine tube from structural reasons. There is therefore a concernthat the smooth flow of the high temperature fluid is significantlyaffected when the cross-sectional area of that serpentine tube isminimized. To address the problem, the cross-sectional area of theserpentine tube disposed in the innermost position on the core plates 53and 54 is configured to be larger than the cross-sectional area of theouter serpentine tube adjacent thereto. The protrusions 10 a to 10 ethat form the serpentine tubes have cross-sectional areas that satisfythe following relationship: the cross-sectional area of the protrusion10 a>the cross-sectional area of the protrusion 10 b>the cross-sectionalarea of the protrusion 10 c>the cross-sectional area of the protrusion10 d and the cross-sectional area of the protrusion 10 b>thecross-sectional area of the protrusion 10 e>the cross-sectional area ofthe protrusion 10 c. It is, however, noted that the configuration of thepresent invention is not limited to the configuration of the presentembodiment, but the cross-sectional area of each of the serpentine tubesor the protrusions 10 can be designed as appropriate. For example, theserpentine tubes described above, including the one disposed in theinnermost position on the core plates 53 and 54, may be designed in sucha way that a serpentine tube disposed in a position closer to the centerof the core plates 53 and 54 and farther apart from the outer ends inthe width direction of the core plates 53 and 54 has a smallercross-sectional area. In this case, the serpentine tubes havecross-sectional areas that satisfy the following relationship: thecross-sectional area of the protrusion 10 a>the cross-sectional area ofthe protrusion 10 b>the cross-sectional area of the protrusion 10 c>thecross-sectional area of the protrusion 10 d>the cross-sectional area ofthe protrusion 10 e.

As described above, in the plate laminate type heat exchanger 100, apair of core plates 53 and 54 forms a plurality of serpentine tubessurrounded by the walls of the protrusions 10 and 10, and the serpentinetubes form the corresponding high temperature fluid compartments. Theserpentine tubes are configured to make a U-turn on the other end sidein the longitudinal direction of the core plates 53 and 54, and bothends of each of the serpentine tubes is configured to converge into theinlet port for high temperature fluid 58 a and the outlet port for hightemperature fluid 58 b, respectively. As a result, the high temperaturefluid flows through the high temperature fluid compartments in theserpentine tubes along the U-shaped path and flows in an arcuate andcircular manner in the vicinity of the inlet port for high temperaturefluid 58 a and the outlet port for high temperature fluid 58 b. That is,in the flow process, the high temperature fluid comes into contact witha large area of the core plates 53 and 54. Consequently, the area of thecore plates 53 and 54 that does not contribute to heat transferdecreases, and the core plates 53 and 54 have a large area thatcontributes to heat exchange between the high temperature fluid and thelow temperature fluid. The heat exchange efficiency between the hightemperature fluid and the low temperature fluid in the plate laminatetype heat exchanger 100 is therefore higher than that in the platelaminate type heat exchanger 500 of related art. Further, the serpentinetubes, except the one disposed at the center of the core plates 53 and54, are configured in such a way that a serpentine tube disposed in aposition closer to the center of the core plates 53 and 54 and fartherapart from the outer ends in the width direction of the core plates 53and 54 has a smaller cross-sectional area. Consequently, in the platelaminate type heat exchanger 100, the high temperature fluid flowsthrough the tubes disposed on the end sides in the width direction ofthe core plates 53 and 54 at a flow volume rate similar to that flowingthrough the tubes disposed at the center of the core plates 53 and 54.As a result, the flow rate of the high temperature fluid flowing throughthe tubes disposed on the end sides in the width direction of the coreplates 53 and 54 is substantially the same as the flow rate of the hightemperature fluid flowing through the tubes disposed at the center ofthe core plates 53 and 54, whereby the flow rates of the hightemperature fluid flowing through all the tubes are substantially thesame. The plate laminate type heat exchanger 100 therefore has moreexcellent heat exchange efficiency. Further, in the plate laminate typeheat exchanger 100, a plurality of slit-shaped second protrusions 50 areformed in the protrusions 10, which form the serpentine tubes. Thesecond protrusions form a more complex flow path in each of theserpentine tubes. Consequently, in the flow process, the hightemperature fluid comes into contact with a larger area of the coreplates 53 and 54 than in a case where no second protrusions 50 areformed in the protrusions 10. As a result, the core plates 53 and 54have a larger area that contributes to the heat exchange between thehigh temperature fluid and the low temperature fluid. The plate laminatetype heat exchanger 100 therefore has still more excellent heat exchangeefficiency.

Other Embodiments

Another embodiment of the present invention will be described withreference to FIGS. 3A, 3B and FIGS. 4A, 4B. FIGS. 3A, 3B and FIGS. 4A,4B show improved portions of a plate laminate type heat exchanger 200according to another embodiment of the present invention. FIGS. 4A and4B show second protrusions 50 formed on protrusions 30 and 40 shown inFIGS. 3A and 3B. In FIGS. 3A, 3B and FIGS. 4A, 4B, the same or similarportions have the same reference characters. No description will,however, be made of the area where the U-turn region is formed.

The plate laminate type heat exchanger 200 shown in FIGS. 3A, 3B andFIGS. 4A, 4B includes front and rear end plates 51 and 52 and aplurality of pairs of core plates 13 and 14 (cores 15) laminatedtherebetween, and peripheral flanges of each of the pairs of core plates13 and 14 are bonded to each other in a brazing process, whereby hightemperature fluid compartments are alternately laminated in the spacesurrounded by the end plates 51, 52 and the core plates 13, 14, and eachof the fluid compartments communicates with pairs of circulation pipes56 a, 56 b and 57 a, 57 b provided on the front end plate 51 in such away that the circulation pipes jut therefrom.

Each of the core plates 13 and 14 is an improved flat plate.Specifically, a plurality of corrugated protrusions 30 and 40 are formedon one side of each of the flat core plates 13 and 14 (except the areawhere the U-turn region is formed), and the corrugated protrusions 30and 40 continuously meander along the longitudinal direction of theplates. Each of the plates is curved in such a way that ridges andvalleys are disposed in the direction in which the plates are laminatedand the ridges and valleys are repeated along the longitudinal directionof the plates. The plurality of protrusions 30 and 40 are disposed inparallel to the longitudinal direction of the core plates 13 and 14 andequally spaced apart from each other. The protrusions 30 and 40 haveridges and valleys formed in the width direction of the core plates 13and 14, and the ridges and valleys meander in such a way that they arealternately and periodically repeated along the longitudinal directionof the core plates 13 and 14. The protrusions 30 and 40 also have ridgesand valleys formed in the direction in which the core plates 13 and 14are laminated, and the ridges and valleys meander in such a way thatthey are alternately and periodically repeated along the longitudinaldirection of the core plates 13 and 14. The ridges and valleys formed inthe width direction of the core plates 13 and 14 are disposed incorrespondence with the ridges and valleys formed in the direction inwhich the core plates 13 and 14 are laminated. The protrusions 30 and 40are waved not only in the direction in which the core plates 13 and 14are laminated but also in the width direction of the core plates 13 and14. The protrusions 30 and 40 are the same in terms of the period, thephase, and the amplitude of the waves formed in the width direction ofthe core plates 13 and 14.

Each of the pairs of core plates 13 and 14 (cores 15) is assembled insuch a way that the side of the core plate 13 that is opposite the oneside on which the protrusions 30 and 40 are formed faces the side of thecore plate 14 that is opposite the one side on which the protrusions 30and 40 are formed and the protrusions 30 and 40 formed on the respectivecore plates are paired but oriented in opposite directions (see FIG.3A). In each of the cores 15, a plurality of serpentine tubes surroundedby the walls of the protrusions 30 and 40 are formed, and the serpentinetubes form the corresponding high temperature fluid compartments. Thecores 15 are assembled in such a way that the ridges (valleys) formed onthe respective core plates in the laminate direction are overlaid witheach other (see FIG. 3B).

The protrusions 30 and 40 oriented in vertically opposite directions arepaired and form the serpentine tubes, and serpentine tubes adjacent inthe width direction of the core plates 13 and 14 do not communicate witheach other. The high temperature fluid therefore separately flowsthrough each single serpentine tube substantially in the longitudinaldirection, but does not flow into other adjacent serpentine tubes. Theconfiguration of the present invention, however, is not limited to theconfiguration described above. For example, the protrusions 30 and 40may be formed in such a way that they are out of phase by half theperiod in the longitudinal direction or the width direction of the coreplates 13 and 14 so that they do not form serpentine tubes (not shown).In this configuration, the high temperature fluid flows into the portionbetween adjacent protrusions, whereby more complex high temperaturefluid compartments are formed. Further, embossments 31 and 41 arepreferably formed on the protrusions 30 and 40 at locationscorresponding to the ridges and valleys formed in the direction in whichthe core plates 13 and 14 are laminated. In this case, when the pairs ofcore plates 13 and 14 are laminated, pairs of upper and lowerembossments 31 and 41 abut each other and form cylindrical members inthe low temperature fluid compartments (see FIG. 3B). The cylindricalmembers support the core plates 13 and 14 in the direction in which theyare laminated, whereby the strength of the plates is improved.

As shown in FIGS. 4A and 4B, second protrusions 50 are preferably formedon each of the walls that form the protrusions 30 and 40 so that each ofthe serpentine tubes has an inner complex structure. That is, smallsecond protrusions 50 are successively formed on each of the walls thatform the protrusions 30 and 40 shown in FIGS. 4A and 4B along thedirection substantially perpendicular to the direction in which the hightemperature fluid flows, and the second protrusions 50 are disposedsubstantially in parallel to the width direction of the core plates 13and 14. As a result, a more complex flow path is formed in each of theserpentine tubes. The present invention, however, is not limited to theconfiguration described above, but the second protrusions 50 may beintermittently formed. The shape, the direction, the arrangement, andother parameters of the second protrusions 50 shall be designed asappropriate. For example, the second protrusions 50 may be formedsuccessively or intermittently along the direction perpendicular to thedirection in which the protrusions 30 and 40 meander or may be formedsuccessively or intermittently along the direction in which theprotrusions 30 and 40 meander.

According to the configuration described above, each of the pairs ofcore plates 13 and 14 form serpentine tubes that meander not only in thedirection in which the core plates 13 and 14 are laminated but also inthe width direction of the core plates 13 and 14. The high temperaturefluid compartment is formed in each of the serpentine tubes, and the lowtemperature fluid compartment is formed in the area sandwiched betweenadjacent serpentine tubes. Since each of the serpentine tubes eliminatesthe need for fins but forms a complex flow path, the heat transfer areaof the core plates 13 and 14 increases. Further, since the length fromthe inlet to the outlet of each of the fluid compartments (path length)increases, the heat exchange efficiency is improved by approximately 10to 20%. The plate laminate type heat exchanger 200 without fins cantherefore maintain heat exchange efficiency equivalent to that obtainedwhen fins are provided. Further, fins can be completely omitted in eachof the cores 15. Moreover, reducing the number of fins or omitting finsallows the number of part and hence the cost to be reduced.

The plate laminate type heat exchanger 200 is configured in such a waythat the high temperature fluid flows through the serpentine tubes fromone end to the other end in the longitudinal direction, and hence has astructure similar to that of a tube type heat exchanger. The platelaminate type heat exchanger 200, however, has complex flow paths andstructurally differs from a tube type heat exchanger in this regard.That is, in a tube type heat exchanger, each fluid compartment is formedof a linear tube and it is structurally difficult to form a serpentinetube that meanders in the laminate and width directions. In a tube typeheat exchanger, it is therefore significantly difficult to form complexflow paths in a tube and in the area sandwiched between tubes. In theplate laminate type heat exchanger 200 of the present invention,however, only laminating the core plates 13 and 14 allows formation ofcomplex flow paths. The heat exchange efficiency between the hightemperature fluid and the low temperature fluid can thus besignificantly improved in the plate laminate type heat exchanger 200.

Other embodiments of the present invention will be described withreference to FIG. 5 and FIGS. 6A, 6B. FIG. 5 is a perspective viewshowing an improved portion of a plate laminate type heat exchanger 300,and FIGS. 6A and 6B show an improved portion of a plate laminate typeheat exchanger 400. In FIG. 5 and FIGS. 6A, 6B, the portions that arethe same as or similar to those in FIGS. 3A, 3B and FIGS. 4A, 4B havethe same reference characters.

As shown in FIG. 5 and FIGS. 6A, 6B, each of the plate laminate typeheat exchangers 300 and 400 has a configuration substantially the sameas that of the plate laminate type heat exchanger 200 shown in FIGS. 4Aand 4B, but structurally differs from the plate laminate type heatexchanger 200 in that the cross-sectional shape of each of theprotrusions 30 and 40 is not substantially rectangular but substantiallyhemispherical. In the plate laminate type heat exchanger 300 shown inFIG. 5, the protrusions 30 and 40 meander along the longitudinaldirection in an in-phase manner, and a pair of protrusions 30 and 40form a serpentine tube surrounded by the walls of the protrusions 30 and40, which are in phase. The serpentine tube has a substantially circularcross-sectional shape and forms a complex flow path that eliminates theneed for fins. As a result, the heat transfer area of the core plates 13and 14 increases in the present embodiment as well. Further, since thelength from the inlet to the outlet of each of the fluid compartments(path length) increases, the heat exchange efficiency is improved.

On the other hand, in the plate laminate type heat exchanger 400 shownin FIGS. 6A and 6B, the protrusions 30 and 40 are configured to meanderalong the longitudinal direction of the core plates 13 and 14 in ananti-phase manner (see FIG. 6A). FIG. 6B is a schematic plan view of theplate laminate type heat exchanger 400 shown in FIG. 6A, and thecross-sectional view taken along the line A-A in FIG. 6B substantiallycorresponds to FIG. 6A. It is noted, however, that FIG. 6B does not showthe second protrusions 50 shown in FIG. 6A.

According to the configuration described above, a pair of core plates 13and 14 form complex flow paths formed by the walls of the protrusions 30and 40, and the complex flow paths allow the high temperature fluid tobe agitated at their intersections. As a result, the heat exchangeefficiency between the high temperature fluid and the low temperaturefluid is significantly improved. The plate laminate type heat exchangers300 and 400 can therefore readily maintain heat exchange efficiencyequivalent to that obtained when fins are provided. Further, fins can becompletely omitted in each of the pairs.

INDUSTRIAL APPLICABILITY

The present invention can provide a plate laminate type heat exchangerhaving high heat exchange efficiency.

1. A plate laminate type heat exchanger comprising: front and rear endplates; a plurality of pairs of core plates laminated between the frontand rear end plates; and high temperature fluid compartments throughwhich high temperature fluid flows and low temperature fluidcompartments through which low temperature fluid flows defined in thespace surrounded by the end plates and the core plates by bondingperipheral flanges of each of the pairs of core plates to each other ina brazing process, each of the fluid compartments communicating with apair of circulation pipes provided on the front or rear end plate insuch a way that the circulation pipes jut therefrom, the plate laminatetype heat exchanger characterized in that a plurality of groove-likeprotrusions is formed on one side of each of the flat core plates, theprotrusions extend substantially in parallel to one another from one endside in the longitudinal direction of the plate toward the other endside in the longitudinal direction of the plate, form a U-turn region inan area on the other end side in the longitudinal direction of theplate, and return to the one end side in the longitudinal direction ofthe plate, the plate is curved in such a way that ridges and valleys areformed on part of the plate, the area in which the protrusions areformed but the U-turn region is not formed, in the direction in whichthe plate is laminated and the ridges and valleys are repeated along thelongitudinal direction, a pair of an inlet port for low temperaturefluid and an outlet port for low temperature fluid are provided on therespective end sides in the longitudinal direction of the core plates,and a pair of an inlet port for high temperature fluid and an outletport for high temperature fluid are provided on one end side in thelongitudinal direction of the core plates in an area inside the areawhere the inlet port for low temperature fluid or the outlet port forlow temperature fluid is provided, both ends of each of the protrusionsconverge into the inlet port for high temperature fluid and the outletport for high temperature fluid, respectively, and each of the pairs ofcore plates is assembled in such a way that the side of one of the twocore plates that is opposite the one side faces the side of the otherone of the two core plates that is opposite the one side and theprotrusions formed on the respective core plates are paired but orientedin opposite directions.
 2. The plate laminate type heat exchangeraccording to claim 1, characterized in that each of the protrusions alsohas ridges and valleys formed in the width direction of the core platesperpendicular to the longitudinal direction of the core plates, and theridges and valleys are repeated along the longitudinal direction of thecore plates.
 3. The plate laminate type heat exchanger according toclaim 2, characterized in that the protrusions formed on each of thepairs of core plates are the same in terms of the period and theamplitude of the waves formed of the ridges and valleys formed in thewidth direction of the core plates.
 4. The plate laminate type heatexchanger according to claim 3, characterized in that the protrusionsmeander in an in-phase manner along the longitudinal direction of thecore plates.
 5. The plate laminate type heat exchanger according toclaim 4, characterized in that each of the pairs of core plates form aplurality of serpentine tubes surrounded by the walls of theprotrusions, and the serpentine tubes form the corresponding hightemperature fluid compartments.
 6. The plate laminate type heatexchanger according to claim 5, characterized in that the serpentinetubes, except the one disposed in the innermost position on the coreplates, are configured in such a way that a serpentine tube having ashorter length has a smaller cross-sectional area.
 7. The plate laminatetype heat exchanger according to claim 3, characterized in that theprotrusions meander in an anti-phase manner along the longitudinaldirection of the core plates.
 8. The plate laminate type heat exchangeraccording to any of claims 1 to 7, characterized in that secondprotrusions are formed on the walls that form the protrusions along thedirection substantially perpendicular to the direction in which the hightemperature fluid flows.